Twelve years after Billie Jean King struck down Bobby Riggs with her blow for women's lib and half a year after Vitas Gerulaitis shot his mouth off at the U.S. Open, the sexes have once again agreed to battle on the tennis court.

The date (Aug. 16 or 23) and the site (Las Vegas or Atlantic City) have yet to be determined, but the match is set--with a total purse of $500,000 at stake.

On the women's side of the net, it's the world's No. 1-ranked doubles team of Martina Navratilova and Pam Shriver. And for the men, it's Riggs, getting in a second dig, and Gerulaitis, getting the chance to show that his actions speak louder than his words.

If that's possible.

It's a novelty attraction, to be sure, and the outcome is not going to alter the history of the sport. But the pairing is a promoter's dream--the hook is a natural--and already, people are biting.

"It's caused a little more interest than we expected," Shriver said. "It's such a wild setup. It's getting a lot more publicity than most tennis events. People right now seem to like things that are different."

This is different, all right. And for Navratilova, whose approach to tennis is as serious as it is overpowering, it's also a radical departure.

She has had similar offers before. Many of them. Promoters tried to line her up against John McEnroe, Ilie Nastase, Derek Tarr (the No. 100 men's player made famous by Gerulaitis at Flushing Meadow). Navratilova, considering such proposals undignified, nixed them all.

Why would she agree to this one?

Navratilova cites three reasons.

"One, I think we're going to win," she said. "Obviously, I wouldn't have done it if I couldn't have picked Pam. You're only as good as your weakest link and with Pam and I, we don't have any weakness.

"Two, the money is going to my foundation (Navratilova's charity for children). That's a lot of money for one day.

"And three, it's doubles. It's not a legitimate thing. You can't get too serious about it. Hopefully, it won't turn into a circus."

Better not get your hopes too high, Martina. Not with Riggs around. At 67, Riggs is still hustling and this is his latest gig. Riggs is not only playing in the match, he's promoting it as well.

"Bobby's so great at the BS and carrying on," Shriver said. "He knows how to create interest. As it gets closer, I know we're going to get asked about it more and more."

Riggs is also the reason why the women believe they are going to duplicate King's triumph of 1973. Call it the age factor.

Navratilova is at her prime at 28. Shriver is 22.

Gerulaitis is still a Top 20 player at 30, although no longer a threat in major tournaments. And Riggs . . . well, he won his last major tournament 44 years ago.

"I honestly think that because of Bobby's condition, we're going to win," Shriver said. "I know the way he plays now and it's getting difficult for him. He's deaf and he wears glasses. He's 67 years old.

"Now, if it was someone like (Pancho) Segura, we would not get two or three games a set. Segura is tough. Riggs is different. He was always more of a finesse player, a little guy who didn't hit with much power."

Navratilova: "It's going to be almost like a mixed doubles match. Bobby is not on the level of Pam and me. I don't know if Bobby can hit as hard as us."

The burden for the men is going to fall on Gerulaitis, according to Navratilova and Shriver. And they wonder if he is up to it.

"Vitas is going to have to be all over the place, and I'm sure he will," Shriver said. "Their only hope is if he carries on like a maniac.

"But Vitas doesn't have that one big weapon. He doesn't have a huge serve. He has a nice forehand, but I assume he'll play the backhand side of the court with Riggs. With Martina's lefty serve and the way I kick the ball pretty well into that corner, I think we can neutralize his forehand.

"And Vitas is going to be as nervous as anyone. He's stuck himself out on the line."

King has said that a victory by Navratilova and Shriver will provide a vital boost for women's tennis, but the contestants themselves say they are motivated by other reasons.

"Hopefully," Shriver said, "we'll be able to shut Vitas up. He can be such a pain sometimes. I don't know if he has a huge chip on his shoulder or if it's part of an act.

"I think he feels that the only way he can get his name in the paper is by running his mouth. His play doesn't warrant that much attention anymore."

Navratilova: "I think Vitas is reaping the benefits of having a big mouth."

And regarding that No. 100 men's player that Gerulaitis said Navratilova couldn't beat . . .

Navratilova still begs to differ.

"I've been playing some mixed doubles lately and talking to the men players," Navratilova said. "They say I'd have a pretty good shot at the 100th player.

"After some of our mixed doubles matches, they come over and say, 'Well, it could get interesting.' "